1. Field of the Invention
The present invention pertains to an improved resilient railroad tie cover having separate resilient pads for use with either timber or concrete railroad ties to increase the resiliency of the rail track system and increase the service life of the railroad ties. More particularly, the invention provides a railroad tie cover for covering either timber or concrete ties in which the specific requirements of the particular system are accommodated by fixing one or more separate elastomer pads in a restraining means provided in the railroad tie cover. The universal railroad tie cover and the separate pads for specific ties and/or vibrational damping requirements allows both the railroad tie cover and the pads to be manufactured and shipped in a flat configuration and thereafter be cut to length and installed to form a three dimensional tie cover at the work site.
The advantages of the invention allow the universal railroad tie cover to be shipped to the work site and fitted with an elastomer pad specifically designed for concrete ties or for timber ties along with the vibration attenuation requirements for the system in which both the universal railroad tie cover and specially designed pads can be cut to accommodate varying lengths for timber or concrete rail ties that is particularly useful in special track sites such as is employed at rail switches. The utilization of one or more restraining grooves for receiving a separate specially designed pad for the universal railroad tie cover or sleeve not only assists in dampening vibration and distributing loads during train passage but also provides improved rail operation by a reduction in noise and an increase in resiliency in rail tracks with or without ballast.
2. Description of the Prior Art
The prior art employs a variety of resilient pads used under the rail and railroad tie covers for covering ties to increase the resilience of railroad track with and without ballast. Conventional railroad track systems in the United States predominantly employ a ballasted bed of crushed stone for supporting wooden railroad ties which impart some resiliency to the railroad system but which result in harder and noisier railroad tracks. In some applications such as in tunnels or in environments where deep beds of ballast are not practical, resilient pads have been interposed between the railroad track and the railroad tie to increase the resiliency of the railroad system. One such application of a rubber pad to increase the resiliency of a rail positioned on a portion of a wooden tie is illustrated in U.S. Pat. No. 2,779,543.
In many track applications in European countries, wooden ties are not utilized and railroad track systems are in widespread use that do not use ballast. To obtain resiliency, elastomer pads or block tie boots which fit over and around the concrete railroad ties are employed. Illustrative of railroad track systems utilizing railroad track without ballast and block tie boots is U.S. Pat. No. 3,289,941. In such systems, resiliency is imparted by employing a rubber boot or sheath interposed between a concrete tie block and the continuous floor formed of cement, concrete or black concrete. Unlike the present invention, such a prior art system does not provide a universal tie cover that can be interchangeably used for a variety of monolithic and two block tie configurations and is not designed to provide drainage and aeration of the ties. Due to the shape of many prior art railroad tie covers, such prior art covers cannot be used with conventional timber ties.
The known prior art systems in use in the United States for railroad timber ties employ rubber pads and similar flat resilient supports to increase the resiliency of the railroad systems. Such systems generally have not been designed for the purpose of increasing the operational life of railroad timber ties by promoting the drainage of water from the wooden rail tie and drawing air into and around the railroad tie during the loading or unloading of the railroad tie systems such as occurs during the passage of trains.
In addition such known prior art systems have not provided the range of applicability of the present railroad tie cover which can be used for both timber and concrete ties. Unlike the prior art the universal railroad tie cover is designed to accept a specially designed pad for timber and concrete tie applications. The railroad tie cover of the present invention is constructed of an elastomer material designed to not only increase the resiliency of traditional railroad beds with or without ballast as utilized in American railroad installations but also to receive and fix one or more specifically designed pads to provide for aeration and vibration attenuation. The novel cover and pad combination is also constructed to receive a separate pad designed to cooperate with the railroad tie cover to increase the life of the railroad tie by allowing moisture to be drained away from both railroad timber and concrete ties while providing necessary aeration to increase the service life of railroad ties. Aeration and removal of moisture also provides advantages to concrete ties particularly where low temperature could result in freezing of water and subsequent cracking of the tie.
In the application of rubber pads to U.S. prior art systems, the flat rubber pad has traditionally been interposed between the wooden tie and the steel tie plate upon which the steel rail is placed in order to impart limited resiliency to the overall system. Unlike the prior art, the present system is directed to the utilization of a resilient covering for receiving one or more specifically designed pads which are inserted into the bottom portion of the tie cover. The present invention employs a railroad tie cover for railroad systems with and without ballast in which the overall resiliency of the system is achieved by employing a universal tie cover which accommodates specially designed pads for concrete and timber ties. The universal pad may have a flat and smooth outside surface of a desired thickness and hardness whereas the inside surface of the pad includes means for receiving and fixing one or more interchangeable and specially designed to provide for vibration attenuation and aeration requirements of the system. The receiving and fixing means on the inside surface of the universal railroad tie cover may be designed to further promote aeration and channeling of water away from the wooden railroad tie.
The invention further provides a railroad tie cover that is particularly advantageous for in the field application to railroad ties as the tie cover and pads are manufactured, shipped and stored in a flat configuration and with a minimum cost as a result of their novel configuration and design. The railroad tie cover is susceptible to extrusion or molding processes to form a flat and substantially rectangular cover having in its bottom portion one or more pad restraining means for fixing the position of one or more separate pads which may thereafter be installed by inserting the desired pads and attaching the universal railroad tie cover to the railroad ties by bending and fastening the sides around the railroad tie. In addition the tie covers and pads can be installed on standard tie lengths or cut to various sizes at the work site to accommodate tie lengths of varying sizes which are predominantly employed at rail switches and other special track work.
The utilization of the novel railroad tie covers of the present invention further allows the dissipation of shock and vibration that impairs the integrity and useful life of the railroad tie fastening system, protect buildings in adjacent areas from structural damage, and alleviates the nuisance of vibrations to occupants of neighboring buildings while at the same time prolonging the useful life of both concrete and timber railroad ties. The utilization of a separate elastomer pad or a plurality of pads in the tie cover center support reduces track hardness and improves the performance of rail systems by a reduction of noise and maintenance on railroad tie systems utilizing wooden and concrete ties.